Production of rayon



March 28, 1961 J. GRISET, JR ETAL 2,977,184

PRODUCTION OF RAYON 5 Sheets-Sheet 1 Filed June 16, l953 ATTORNEY 5 Sheets-Sheet 2 ATTORNEY wn" .w H M @RN j March 28, 1961 E. J. GRISET, JR., EIAL PRODUCTION OF RAYON Filed June 16, 1953 March 28, 1961 E. J. GRISET, JR., ETAL 2,977,184

PRODUCTION OF RAYON Filed June 16, 1953 5 Sheets-Sheet 3 win w IIAIW/gg" BY hw/fw ATTORNEY March 1951 E. J. GRISET, JR, ETAL 2,977,184

PRODUCTION OF RAYON Filed June 16, 1953 5 Sheets-Sheet 4 INVENTORS EF/VESTJ fifi/szzde w,

ATTORNEY March 28, 1961 E. J. GRISET, JR, ET AL 2,977,184

PRODUCTION OF RAYON Filed June 16, 1953 5 Sheets-Sheet 5 lb mkve x 8k 2 5 R O T N E V m fRA/AWJ @WSEzJe 5/4 8597' A THUR/wow ATTORNEY PRODUCTION or RAYON Ernest J. Griset, In, and Gilbert I. Thurm'ond, Asheville, N.C., assignors to American Enka Corporation, Enka, N.C., a corporation of Delaware Filed dune '16, 1953, Ser. No. 362,016

4 Claims. (Cl. 18-54) This invention relates to the treatment of filamentous material such as threads, filaments, fibers, yarns and the like, hereinafter referred to generically as threads; and more particularly to a method for the continuous production of freshly spun viscose rayon threads having improved properties. In its more specific aspects, the invention relates to a method for continuously spinning im- .proved high tenacity rayon threads in a tube spinning system. I

In US. Patent No. 2,725,276, there are disclosed a method and apparatus for producing synthetic threads by the so called Griset tube spinning method. The present invention utilizes the concept of tube spinning disclosed in the latter case in the manufactureof high tenacity viscose rayon. An entirely new machine which incorporates the Griset tube spinning principle has been developed for the production of high' tenacity viscose rayon threads. This apparatus is the subject matter of copending application Serial No. 361,892, filed June 16, 1953. The present application is concerned primarily with the method for producing improved high tenacity thread in this apparatus;

It is an object of the present invention to provide a method for utilizing the Griset tube spinning principle to produce viscose rayon thread having improved properties.

A further object of this invention is' to provide a continuous tube spinning process for the production of high tenacity viscose rayon threads.

A still further object ofthe invention is to produce a continuous high tenacity viscose rayon thread having improved physical properties.

Other objects and advantages of the invention will be apparent upon consideration of the following detailed description. I I

In general, the present invention comprises a process for producing a high tenacity viscose rayon thread wherein the conditions in the spinbath, in the aftertreating 2,977,184 Fl tb M2128: .5,!

F ice The invention will be further explained by reference to the annexed drawings, wherein Figure 1 is a section in side elevation of part of the spinning machineused in the present invention;

Figure 2 is a plan view of a group of treating tubes used for a single spinning position;

Figure 3 is a view in side elevation of the group of treating tubes shown in Figure 2; I

Figure 4 is a perspective view of the back side of a spinning machine used in the present invention; I I

Figure 5 is a side elevation of the drying assembly used in the present invention; and I Figure 6 is a diagrammatic flow sheet of the liquid circulation system used in the invention. I

Referring now to Figure 1, viscose solution is extruded through spinneret 10 into acid coagulating bath 11 to produce thread 12. The thread 12 is wrapped several times around small godet 13, passed downwardly to roller 14 and then upwardly to large godet 15 where it is also wrapped several times around. The peripheral speeds of the two godets are adjusted so as to impart a stretch of about 75% to the thread. Roller 14 is submerged in a second bath 16 and the thread 12 passes through this bath 16 during its travel between small godet I3 and large godet 15. It Will thus be apparent that the stretching of the thread 12 occurs just before, during and after the time that it is being subjected to the treatment of the second bath 16.

Upon leaving the large godet 15, the thread 12'' is passed downwardly and is intercepted by a stream of liquid issuing from jet 17 by which it is propelled into and through a treating tube 181 A detailed description of the manner in which the thread 12 is initially spunin' and introduced into the tube 18 will not bev given here inasmuch as this procedure is fully described in US. Patents Nos. 2,675,690 and 2,725,276, to each of which reference is hereby made.

Upon leaving the tube 18, the thread 12 is discharged into a jet box 19. The thread entering the box 19 from the tube liifirst' passes along deflector 2i? and then it is liquid propelled in succession through treating tube 21, deflector 22, tube 23, deflector 2.4, tube' ZS, deflector 26, tube 27, deflector 28, tube 29, deflector 30, tube 31,

deflector 32 and finally tube 33 zones, and during the final drying operation, are careafter, the said material is dried, rewet, restretch'ed and redried' under tension. Since-the process of the present invention is carried-out in an extremely short time, it is I surprisingtliat the viscose rayon thread'obtained has proper'ties. in mo t instances better than thread roduced ae- 'cording t'ocohventionaf methods; a I 1 I, The defiectors2il, 24, 28 and 32 are mounted on a bar 34 for laterally shifting to and from a position registering with the entrance ends" of tubes 21, 25, 291 and 33, respectively (see Figure 2) Deflectors 22, 26 and 30 are mounted'on a bar 35' similar in structure and function to' the bar 34. it will .be apparent from Figures" 2 and 3 that separate liquid recovery compartnientsunderlie the, deflectors in registry with the exit e'ndIof the treating tubes. When spinning -in is completed each aftertreating tube, except tube 33, discharges'into a com'- partment and each compartment has a drain by which the liquid recovered therein can be recycled. As seen in Figure 2, the thread reverses its direction of. travel tions in the tube assembly are more-or less-automatic; and manual handling of the thread-during regeneration.

at the' end of" each tube. While passing through these eight treating tu s theth a sm t o l n yed by the liquid but issubjectjedto treatment wi '1 vsyi s. i u dt 9mrk 1 r ne e s t e s thread. Referring nowto Figure .3, supply headers 18d, 21a,23 ;;25a,27a, 29 staand 33a furnish liquids to the corresponding treating tubes: 1 I I I, I I

Inasmuch as the spinnin'g in and 'aftertreating" openiis not required, treating liquidsfhaving hightemperatures may befemployed." For exar'nple, treating lii uids having I I atemp eratu're of 9b C: ti a've'be n empl' d'intheabeve described tubetreating pmcess;- The use or these er.

temperatures alone.

through the entire aftertreating system in a remarkably short time. For example, at a spinning speed of about 76 meters per minute, it has been found that the thread passes through eight treating tubes 32 inches in length in around seven seconds. In view of the fact that not more than seven or eight seconds are required for the thread to pass from the initial spinning bath ll. through the stretching operation and into the first treating tube 18, the total time required for transforming viscose solution into a substantially completely regenerated and finished viscose rayon thread is less than twenty seconds. Considering the manifold physical and chemical changes which occur during this transformation, the shortened treating time is indeed phenomenal.

It is important to note that the abbreviated treating time mentioned above is not achieved by the use of high An even more important factor is the tension conditon of the thread during the aftertreatment. Since the thread is conveyed through the treating tubes solely by the passage of the liquid flowing through the tubes, it is subjected to a negligible tension during the time it .is being aftertreated. The tension on the thread 12 is only about grams as it enters tube 18 and it has been found that this tension does not change appreciably as the thread proceeds through the other tubes. By observation it is apparent that the thread in the tubes is in a substantially relaxed condition; the filaments are fully separated and dispersed with the liquid freely penetrating between them. This relaxed condi tion of the yarn is of primary importance in the practicing of the present invention.

In a typical aftertreating arrangement tube 18 is sup- 1 plied with water containing 0.16% H 50 at 90 C., tube 21 is supplied with 4% sulphuric acid at 90 C., tube 23 with water containing 0.1% sulphuric acid at 90 C., tube 25 with water at 90 C., tube 27 with 0.09% sodium bicarbonate at 90 C., tubes 29 and 31 with water at room temperature and tube 33 with 1% Nopco at room temperature. Even without a specific desulphurization treating liquid the sulphur content of the treated thread is abnormally low, usually less than 0.05%. The high degree of sulphur removal is believed to be at least partly due to the dispersed condition of the individual filaments during aftertreatment.

The term Nopco as used herein refers to a finishing solution sold by Nopco Chemical Co., Harrison, N.J.,

under the trade name Nopco 2169-M," containing mineral oil blended with emulsifying materials.

Upon passing from the exit end of tube 33, the thread v12 and the finishing solution empty into extension tube 36 and are carried to a position above trough 37. The

finishing solution falls into trough 37 and is carried away for recirculation. The thread 12 leaving the extension tube 36 is guided through combs generally indicated with the numeral 38 in Figure 4, in a path parallel with, but overlying, trough 37 to the end of the spinning machine where it is drawn off in Warp form by means of draw rolls 39. The manner in which the various threads issuing from the finishing tube extensions arebrought together for the purpose of forming a warp sheet, is believed tobe obvious from Figure .4. For a more detailed explanation of the method for forming the warp sheet,

reference is made to US. Patent No. 2,789,339.

.ond series of drying cylinders 58-69, inclusive. Thesecend series of drying cylinders 5849, inclusive, are preferably operated at a speed slightly in excess of squeeze rolls 55, 56, 57, to impart an additional stretch to the once dried threads. On leaving the final drying cylinder 69, the warp of threads is passed to any suitable take-up for a continuously running filamentary material.

The propulsion of the drying cylinders iii-5i, inclusive, is effected by a driving chain 7% which interconnects the cylinders, the drive being imparted to the system through a sprocket 71 coaxial with drying cylinder 44. Sprocket '71 is driven from a chain 72 which in turn is driven from a transmission system generally designated by numeral 731 Drying cylinders 5849, inclusive, are similarly driven by an interconnecting chain 74 and power is supplied to the group through a sprocket 75 coaxial with cylinder 65.

Upon reference to Figure 6 a typical liquid circulation system for aftertreating tire yarn can be seen. In that figure the supply and exhaust manifolds are represented as blocks and all of the seventy-two tubes through which the liquids pass from one manifold to the other are represented by a single solid line numbered to cor-respond to the appropriate treating tube of Figure 2.

Beginning then with the tubes 18, it is seen that they are supplied with hot water from a tank 8- and that manifold 13b drains to sewer. Water is supplied to tank S1 through a temperature control heater 76 by a pump 77 which draws from a recovery tank 11-31. which re ceives from manifold 23]) the discharge from tubes 23. Tubes 23 are supplied from manifold 23a which is fed from tank S3. Tank 8-3 is supplied by a pump 78 which delivers Water from recovery tank R-3 through a temperature control heater 79. The water in tank R-3 is recovered from manifold 25b by tubes 25. Tubes 25' are supplied from a tank 8-4 through manifold 25a. The tank S4 receives its water through a heater element 80 from a pump 81 drawing from a tank R4. Tank R-4 is supplied from manifold 2% which is fed by tubes 29 which in turn are supplied by manifold 29a. Mani fold 29a is supplied from tank 8-6 which is fed from tank R-6 by a pump 82 delivering through a heater element 83. Tubes 31 are supplied with fresh soft water heated to the proper temperature. This water is discharged from tank S-7 through manifold 31a. The recovery from tubes 31 is received in manifold 31b and delivered to recovery tank R-6.

It can now be seen that for treating tire yarn the first, third, fourth, sixth and seventh tubes of each group may contain water. The water which first contacts the newly spun yarn has already contacted yarn on four previous occasions and it is not until the fifth water treatment that the yarn encounters fresh water.

In the second tube of each group, the tubes 21, the yarn is treated with sulphuric acid supplied to tank R-2 and delivered from it by pump 84 through heat control element 85 to supply tank 8-2. The tank S-2 feeds manifold 21a and the recovery manifold 21b feeds back to tank R-Z. Make-up liquid is supplied to tank R-2 as indicated in Figure 6.

The fifth tubes of each group, tubes 27, are supplied with NaHCO by a system identical to acid supply system for tubes 21. Sodium bicarbonate recovered from manifold 27b is discharged into tank R-S from which pump 86 delivers it through a heat control element 87 to tank S-5. From supply tank S5 the sodium bicarbonate is delivered to manifold 27a.

The only other solution is finishing solution which is delivered from the tank 8-8 to the tubes 33 from the manifold 33a. This solution is not recovered in a mani fold at all but passes from the tubes 33 through the large tubes 36 into the trough 37. The finishing solution stays with the yarns as they move along the trough during spinning-in and it'moves parallel tothe warp ofvyarns running above the trough37 during the remainder of the doif. At 'theiend .of the trough'aZthe finishing solution is discharged to a screened tank'r'narked .R-Sl in Figure 6. From the recovery tank, to which make-up may be added through line 88, a pump 89 delivers the solutionto tank S-8. If further finish is supplied to the yarns while they are being dried running as a warp, the slasher pair 54 may be supplied in parallel with the tubes 33 as can' be seen in Figure 6.

In Figure 6 all of the supply tanks are shown as above the recovery tanks. The supply tanks are disposed higher than the tube groups to give a uniform head or pressure at the supply manifolds which, in turn, results in uniform flow through the tubes. By arranging the heaters between the recovery tanks and the supply tanks, the likelihood of entraining air is reduced.

Example I Aviscose solution containing 7.3% cellulose, 6.8% caustic, 2.25% sulphur, and having an ammonium chloride number of 11.5, was extruded into a spinbath containing 7.2% sulphuric acid, 17% sodium sulphate, 3.4% zinc sulphate, and 26 ppm. lauryl pyridinium chloride to produce a thread of 1650 denier, 720 filaments. The temperature of the spinbath was 70 C. The coagulated thread was passed upand around small godet 13 and then back down under roller 14 submerged in a second bath containing 2.5% sulphuric acid at 90 C. Upon leaving the second bath, the thread was passed to large godet 15 driven at a speed faster than godet 13 with the result that a stretchof about 75% was impartedt'o the thread between the small godet13 and the largeg 'odet .1'5.

The thread was next passed at a speed of about 76 meters per minute through a series of eight treating tubes by means of a jet of liquid introduced at the entrance end of each tube. While being propelled through the eight treating tubes, the thread was subjected to treatment with the following liquids in the order given: recycled water containing 0.16% H 80 at 90 C., 4% sulphuric acid at 90 C., recycled water containing 0.1% H 80 at 90 C., recycled water at 90 C., 0.09% sodium bicarbonate at 90 C., recycled water at 90 C., water at 90 C., and finishing solution at room temperature. The term recycled water used in reference to the treating liquids refers to water which had been used in at least one previous treating step without subsequent purification. The thread leaving the tube containing the finishing solu tion was drawn off in a warp sheet of similarly treated threads by means of draw rolls 39. The warp sheet was stretched about 1% and dried by passing it into contact with a first series of steam heated drying cylinders. The dried warp was stretched about 4% more during which time it was re-wet by passage through bath 54. The warp of threads was withdrawn from the bath 54 by means of driven squeeze rolls 55, 56, 57, and passed to a second series of drying cylinders rotating at a'speed sufiicient to impart about 1% additional stretch to the threads between the squeeze rolls 55-57 and the second series of drying cylinders. The re-dried threads were taken up in package form on a winding machine. The thread produced had the following properties:

Dry strength, gms./ 100 denier 334 Dry elongation-total, percent a 12.6

Cond. strength, gms./ 100 denier 282 Cond. total elongation, percent 15.4

US. Rubber fatigue 512 Example 11 A viscose solution similar to the one used in Example I was extruded into a spinbath of the composition given in Example I. The coagulated thread of 1650 denier, 720 filaments, was stretched about in a second bath containing dilute sulphuric acid at C.

The thread was aftertreated by passing it through a series of six treating tubes by meansof a jet of liquid introduced into each tube. The thread passing through was drawn off in a warp sheet of similarly treated threads and re-stretched and double dried according to the conditions given in Example I. The redried threadswere taken up in package form on a windingmachineand had the following properties:

Dry elongation-total, percent 11.9 Cond. strength, gms./ denier 285 Cond. total elongation, percent 14.1

US; Rubber fatigue '52s It has been found that the double drying procedure used in the above examples definitely contributes to su perior properties in the finished thread. Samples of thread produced in a similar process involving only a single drying step at times equaled in physical propertiesthe thread produced by the double drying procedure. However, in general, better strength andmore uniform strength was found in thread produced with the double'drying technique. The fatigue values were also better in the double dried thread. p

In order to obtain the most'favorable results it is desirable'to carefully control the acid'concentration in the spinbath whileat the same time controlling the ratio ,betweenthe acid. concentration andthe salt concentration in the spinbath. Calculating the acid/ salt ratio as total weight of sulphuric acid total weight of sodium sulphate it is desirable that the ratio be maintained within the limits 0.35 to 0.50, and preferably at a ratio of about 0.42. While maintaining the foregoing ratio, the best quality threads are obtained when the acid concentration in the spinbath is held within the range of 6.5% to 8.0% sulphuric acid. At acid concentrations below 6.5% the fiber quality of the high tenacity thread becomes markedly inferior. When the acid concentration is appreciably higher than 8.0% the desired physical properties aredifiicult to obtain.

Therefore, by calculating the sodium sulphate content from the above formula, it is seen that the sodium sulphate should be between 13-23 with the preferred range being 1619%.

What is claimed is:

1. A process for continuous production of viscose rayon thread comprising the steps of extruding viscose into filamentary material in an acid coagulating and regenerating bath containing between 6.5 and 8.0% sulfuric acid and maintained at a temperature of at least 65 C., stretching the resultant partially regenerated filamentary material between 50 and 100% and subjecting the said material to an aftertreatment while propelling it successively through a series .of spaced generally horizontally disposed confined liquid treating zones solely. by means of a flowing liquid in each zone, the after treating liquids in at least four of said zones being maintained at a temperature of at least 70 C. with said material being exposed to said liquids for a total time of not more than 30 seconds, whereby a high tenacity thread is produced.

2. A process for continuous production of viscose rayon thread comprising the steps of extruding viscose into filamentary material in an acid coagulating and regenerating bath containing between 6.5 and 8.0% sulfuric acid and maintained at a temperature of at least 65 C.,

stretching the resultant partially regenerated filamentary material between 50and 100%, subjecting the said mate- ,rial to an aftertreatment while propelling it successively ing liquid in each zone, and thereafter drying, rewetting and redrying said treated filamentary material, the aftertreating liquids in at least four of said zones being maintained at a temperature of at least 70 C. with said material being exposed to said liquids for a total time of not more than 30 seconds, whereby a high tenacity thread is produced.

3. A process for continuous production of viscose rayon thread comprising the steps of extruding viscose into filamentary material in an acid coagulating and regenerating bath containing between 6.5 and 8.0% sulfuric acid and maintained at a temperature of at least 65 C., stretching the resultant partially regenerated filamentary material between 50 and 100%, subjectingthe said material to an aftertreatment while propelling it successively through a series of spaced generally horizontally disposed confined liquid treating zones solely by means of a flowing liquid in each zone, and thereafter drying said material under tension, :rewetting and redrying said treated .filamentary material, the aftertreating liquids in at least four of said zones being maintained at a temperature of at least 70 C. with said material being exposed to said liquids for a total time of not more than 30 seconds, whereby a high tenacity thread is produced.

4. A process for continuous production of viscose rayon thread comprising the steps of extruding viscose into filamentary material in an acid coagulating and regenerating bath containing between 6.5 and 8.0% sulfuric acid and between 16 and 19% sodium sulfate and maintained at a temperature of at least 65 C., stretching the resultant partially regenerated filamentary material between and 100%, while treating it with a solution containing dilute sulfuric acid and maintained at a temperature of about 90 C., subjecting said filamentary material to an aftertreatment while propelling 'it successively through a series of spaced generally horizontally disposed confined liquid treating zones solely by means of a flowing liquid in each zone, said aftertreatment including the steps of washing the filamentary material with water maintained at a temperature of at least C., treating the filamentary material with dilute sulfuric acid and treating the filamentary material With a solution of sodium bicarbonate, applying a finish solution to the treated material, thereafter drying said material under tension, rewetting, and redrying said filamentary material under tension, the aftertreating liquids in at least four of said zones being maintained at a temperature of at least 70 C. with said material being exposed to said liquids for a total time of not more than 30 seconds, whereby a high tenacity thread is produced.

References Cited in the file of this patent UNITED STATES PATENTS 1,427,238 Sinkwitz Aug. 29, 1922' 1,871,100 Walton et al Aug. 9, 1932 2,203,793 Lovett June 11, 1940 2,348,415 Polak May 9, 1944 2,369,191 Thurmond Feb. 13, 1945 2,491,938 Schlosser et al Dec. 20, 1949 2,725,276 Griset Nov. 29, 1955 2,725,277 Rilling et al Nov. 29, 1955 

1. A PROCESS FOR CONTINUOUS PRODUCTION OF VISCOSE RAYON THREAD COMPRISING THE STEPS OF EXTRUDING VISCOSE INTO FILAMENTARY MATERIAL IN AN ACID COAGULATING AND REGENERATING BATH CONTAINING BETWEEN 6.5 AND 8.0% SULFURIC ACID AND MAINTAINED AT A TEMPERATURE OF AT LEAST 65*C., STRETCHING THE RESULTANT PARTIALLY REGENERATED FILAMENTARY MATERIAL BETWEEN 50 AND 100% AND SUBJECTING THE SAID MATERIAL TO AN AFTERTREATMENT WHILE PROPELLING IT SUCCESSIVELY THROUGH A SERIES OF SPACED GENERALLY HORIZONTALLY DISPOSED CONFINED LIQUID TREATING ZONES SOLELY BY MEANS OF A FLOWING LIQUID IN EACH ZONE, THE AFTER TREATING LIQUIDS IN AT LEAST FOUR OF SAID ZONES BEING MAINTAINED AT A TEMPERATURE OF AT LEAST 70*C. WITH SAID MATERIAL BEING EXPOSED TO SAID LIQUIDS FOR A TOTAL TIME OF NOT MORE THAN 30 SECONDS, WHEREBY A HIGH TENACITY THREAD IS PRODUCED. 